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Infection and Immunity, March 2001, p. 1739-1746, Vol. 69, No. 3
Institut für Prophylaxe und
Epidemiologie der Kreislaufkrankheiten,1 and
Max von Pettenkofer-Institut für Medizinische
Mikrobiologie,2
Ludwig-Maximilians-Universität, 80336 Munich, Germany
Received 29 September 2000/Returned for modification 11
November 2000/Accepted 30 November 2000
Lyme borreliosis is a multisystemic disorder primarily
affecting the skin, nervous system, and joints. It is caused by the spirochete Borrelia burgdorferi sensu lato and is
transmitted via ticks of the Ixodidae family. Persistence
of borreliae within macrophages has been implicated in the
often chronic history of borreliosis. The uptake of B. burgdorferi by professional phagocytes occurs predominantly by
coiling phagocytosis, a host cell-driven process in which single
pseudopods wrap around and engulf the spirochetes. In the present
study, we investigated the molecular machinery and the signal
transduction pathways controlling the formation of these unique uptake
structures. We found that the phagocytosis of borreliae by primary
human macrophages is accompanied by the formation of
f-actin-rich structures, which in their morphological organization
correspond well to the earlier described coiling pseudopods. Further
experiments revealed that Wiskott-Aldrich Syndrome protein and Arp2/3
complex, major regulators of actin polymerization, are
also recruited to these sites of actin accumulation. In addition,
inhibition of an upstream regulator of Wiskott-Aldrich Syndrome
protein, the Rho-family GTPase CDC42Hs, greatly inhibited the
occurrence of borrelia-induced phagocytic uptake structures. Inhibition
of Rac1, another Rho family GTPase, had a less-pronounced inhibitory effect, while blocking of Rho activity showed no discernible influence. These results suggest that basic mechanisms of actin polymerization that control other types of phagocytosis
are also functional in the formation of the morphologically unique
uptake structures in coiling phagocytosis. Our findings should enhance the understanding of the infection process of B. burgdorferi and contribute to devising new strategies for
countering Lyme disease.
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.3.1739-1746.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Coiling Phagocytosis of Borrelia burgdorferi
by Primary Human Macrophages Is Controlled by CDC42Hs and Rac1 and
Involves Recruitment of Wiskott-Aldrich Syndrome Protein and
Arp2/3 Complex
*
Corresponding author. Mailing address: Max von
Pettenkofer-Institut, Ludwig-Maximilians-Universität,
Pettenkoferstr. 9a, 80336 Munich, Germany. Phone:
49-89-5160-5231. Fax: 49-89-5160-4757. E-mail:
Bettina.Wilske{at}mvp-bak.med.uni-muenchen.de.
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